1. Field of the Invention
The present invention relates to a mixing apparatus for mixing materials having different phases such as liquid and gas by using acoustic resonance.
2. Description of the Prior Art
In general, mixing devices have been used to mix materials having different phases such as liquid-gas or liquid-solid in fermenters such as for beer and microorganisms and waste water disposal processes. To effectively mix the materials, it is proper to maximize a contact area between the materials and perturb the equilibrium state therebetween so as to narrow an interface layer thickness therebetween. Particularly, when the gas to be mixed with the liquid is dispersed, the contact area therebetween widens so that the gas and liquid are effectively mixed with each other.
Note should be made of the fact that a mixing apparatus using vibration is disclosed in U.S. Pat. No. 3,108,749 entitled "Vibratory apparatus for atomizing liquids" and in U.S. Pat. No. 3,917,233 entitled "Vibrator".
FIGS. 1 and 2 also show a mixing apparatus for dispersing gas by narrowing thruholes through which gas passes. Assuming the mixing apparatus is utilized in a waste water dispersing plant, the mixing apparatus will be explained below.
FIG. 1A is a perspective view of a conventional mixing apparatus and FIG. 1B is a sectional view taken along line III--III shown in FIG. 1A.
Referring now to FIGS. 1A and 1B, pressurized air from a compressor (not shown) is supplied into a pipe 11 through a connecting portion 14 and a joint 13. Pipe 11 is made of ceramic or polyethylene, is formed with a plurality of fine holes 11a and is placed in waste water. The air supplied into pipe 11 is dispersed through holes 11a while passing through pipe 11 and penetrates into the waste water, thereby fermenting microorganisms contained in the waste water.
In the above mixing apparatus, the amount of air supplied into the waste water is determined size by the hole formed at pipe 11. However, there may be a lower limit in fining the hole size, so it cannot be always satisfied by a client.
Also, since underwater plants which inhabit in the waste water sometimes block the fine holes, the pipe must be cleaned periodically.
FIG. 2A is a sectional view of another conventional mixing apparatus and FIG. 2B is a plan view of the apparatus shown in FIG. 2A.
Referring to FIGS. 2A and 2B, pressurized air is supplied into a housing 21 through an inlet portion 21a by a compressor (not shown). The air then passes through an intermediate net 22 and a cover net 23 so as to disperse the air into the waste water. At this time, balls 24 float in housing 21 so as to collide with the inflowing air and also disperse the air.
However, the above mixing apparatus is also restricted in the fineness of the net meshes, so mixing efficiency is not satisfactory.